Area forecast discussion
National Weather Service Wilmington Ohio
634 am EDT Monday may 20 2013
Synopsis...
a middle level ridge will build across the region today. The ridge
will move east tonight as a large upper level low over the
northern plains begins to make a slow progression to the east.
The threat for showers and thunderstorms will increase Tuesday
into Wednesday as the low continues toward the Great Lakes. A cold
front will eventually push through our area Wednesday into Wednesday
night. Above normal temperatures along with a humid airmass will
remain in place until after frontal passage.
&&
Near term /until 6 PM this evening/...
a middle level ridge is forecast to build across the region today. Before
it does...a weak warm front/boundary will cross the area this
morning. High resolution models suggest that this feature along
with a weak low level jet may be enough to pop a shower or
storm...so have carried low chance probability of precipitation.
For this afternoon...a very warm and humid airmass will prevail.
With the ridge in place...convection should be held at Bay.
However...with moderate to strong instability along with a very
weak cap...it is not out of the question that an isolated shower
or storm could pop. Given that this chance is about 10
percent...have left the forecast dry for the afternoon hours.
Highs today will warm into the upper 80s with a few spots possibly
reaching 90 degrees before the afternoon is through.
&&
Short term /6 PM this evening through Thursday/...
have used a blend of the GFS...CMC and European model (ecmwf) for the short term
forecast.
Middle level ridge will move east tonight as a large upper level low over
the northern plains pushes slowly east toward the Great Lakes.
Chances of showers and thunderstorms will encroach the western
zones as models suggest that a weakening complex approaches the
region.
On Tuesday...very warm and humid conditions will continue. Timing
and coverage of convection will be dependent on previous feature
moving into the area which is still sketchy at this time. As a
result...have gone with chance probability of precipitation. Given increasing shear and
moderate to strong instability...a few severe storms will be
possible.
For Tuesday night...the threat for showers/storms will
continue...but models suggest that we may be in a relative lull
before a more bonafide shortwave and associated cold front affect the
region on Wednesday.
For Wednesday into Wednesday night...upper level low will drop
southeast into the Great Lakes. As mentioned...a more bonafide
shortwave is expected to rotate NE across the area along with a surface
cold front. Although shear will be moderate...instability will be
a little less than Tuesday given clouds and slightly cooler
temperatures. Even so...can not rule out a few severe storms
during the afternoon into the evening hours.
On Thursday...upper level low will drop southeast into our area. Models
suggest that a secondary cold front/trough axis will approach the
region from the northwest...keeping the threat for showers and
isolated storms. Temperatures will be cooler given clouds and cold air advection
with highs ranging from the upper 60s northwest to the middle 70s southeast.
&&
Long term /Thursday night through Sunday/...
as the secondary front/trough axis shifts south Thursday night...
precipitation should taper off from north to south.
High pressure and a cooler airmass will build down from the north
through the day on Friday. This will lead to slightly below normal
temperatures with highs on Friday in the upper 60s to lower 70s. The
airmass will then slowly moderate through the weekend as middle level
ridging begins to work in from the west. By Sunday...temperatures
will be back to near normal with highs pushing back toward the middle
70s. Will maintain a dry forecast through the weekend at this point
but the 12z European model (ecmwf) and to a lesser extent the 12z GFS are hinting at
the possibility of some short wave energy dropping down in northwest
flow late in the period.
&&
Aviation /10z Monday through Friday/...
with wind flow never completely dissipating
overnight...visibilities for most of the taf sites remained in the
MVFR/VFR range (aside from kluk). Early this morning...some
stratus has been developing...and IFR ceilings appear possible for
a short period of time in the Dayton and Columbus areas.
The atmosphere this afternoon will be very unstable...but with
little to no forcing to help develop thunderstorms...and a cap in
place to also limit free convection from occurring. So...a dry set
of tafs will be issued. By evening...a few computer models
indicate the possibility of storms moving in from the west as they
gradually weaken. The signal for this scenario has been
intermittent and in poor agreement in terms of timing and
placement...so this will be left out of the tafs. South-southwest winds today
will gust to around 20 knots...with VFR cumulus expected to
develop.
In general...conditions overnight are not expected to change
significantly...with south-southwest winds that remain in the 5-10 knot range.
This will make fog unlikely. As mentioned above...there is some
degree of possibility in thunderstorms moving into the area
overnight...which would certainly complicate the tafs well beyond
what is currently in the forecast.
Outlook...thunderstorms will be possible from Tuesday through
Thursday.
&&
Iln watches/warnings/advisories...
Ohio...none.
Kentucky...none.
In...none.
&&
$$
Synopsis...Hickman
near term...Hickman
short term...Hickman
long term...Hickman/jgl
aviation...hatzos
